This operates though Oct-28 this year, running on the tracks used by the Saratoga and North Creek Railroad, which sadly has now suspended tourist operations. But, as you can see from the photos - lots of equipment still on site.
But back to the rail biking. The idea is to offer people an easy way to experience scenery and terrain accessible only by rail, in a more up-close manner than you might riding in a train. There's clubs which purchase and use old railroad 'speeder' (maintenance cars) for this, but this bikes open up the rails to a much broader group.
And, it's quiet, provides some exercise, and is available to anyone.
Here's the 'bike' used by this operation; we reserved a 4-seater but 2-seaters are also available. There are other models, used by other companies - such as Rail Explorers, in other locations.
But it's also very pleasant to simply drift thru the woods. The guides keep the bikes maybe 100' or so apart (or further if you like), so it's not crowded.
And then of course, I had to explore the rest of the area, and a lot of old Delaware & Hudson stuff scattered around.